This invention relates to the field of tissue storage and distribution.
It has been a priority in the medical community to develop a skin wound dressing which will encourage new growth while preventing fluid loss and infection following skin wounds from burns, ulceration, or surgical excision. Traditional bandages and dressings fail to protect large-scale wounds adequately, therefore various alternatives have been developed. Among these are split- and full-thickness grafts of cadaver or porcine skin, and human allografts and autografts. Most have proved unsatisfactory since all but autografts eventually are rejected by the body in the absence of immunosuppressive therapy. Autografts are useful in small areas, but use of conventional autografting technique is not practical for massive burn injury involving large body surface areas. Cultured sheets of epithelial cells for use as skin wound dressings are now available commercially from Biosurface Technology, Inc. of Cambridge, Mass.
Currently, cultured grafts are delivered directly to the operating room at the burn center or hospital for application to the patient. Each graft package consists of a layer of cultured epithelium attached with surgical clips to a backing of petrolatum gauze. Each cultured graft is approximately 25 cm.sup.2 in size and is individually packaged in a shallow dish containing a small amount of serum-free, sodium bicarbonate buffered medium which contains antibiotics. Multiple dishes containing the grafts are shipped in a sterilized gas-tight container. The transport container must be gas tight, since the sodium bicarbonate buffered medium requires 10% CO.sub.2 for maintenance of proper pH.
Problems that have been encountered with the current transport system include spillage of medium from shallow tissue culture dishes into the sterilized transport box, loss of the gas tight nature of the box during transit, resulting in grafts being maintained in medium at basic pH for an unknown period of time, and detachment of the epithelium from the vaseline gauze backing, due to shear forces of medium sloshing around during transit.
The use of these grafts as skin wound dressings also presents other practical difficulties. The tensile strength of the grafts is such that they often cannot support their own weight and tear if suspended by an edge. For this reason, the grafts are attached to gauze to allow easier handling. Once a graft has folded over upon itself it is very difficult to restore to its original planar configuration, and essentially impossible without the gauze backing. Handling of the grafts should be kept to a minimum since handling causes a significant, measurable reduction in cell viability.
The object of this invention is to provide a specially designed container for storage and distribution of a skin wound dressing which allows a minimum of handling and easy removal so that maximal viability of the dressing is maintained prior to application to skin wounds arising from burns and other injuries. The object is achieved by the provision and use of a gas-tight sealable container for individual grafts. The containers, once sealed, are gas-tight and spill proof. In addition, since the grafts are stored with minimal air space, shear forces that tear the graft away from its backing are reduced.